French patent 2 413 205 and European patent 0 438 339 in the name of the Applicant company disclose methods of manufacturing articles of molded plastics material that make it possible to imitate the appearance of stone, of marble, or of mother-of-pearl.
Those methods make it possible, in particular, to improve the appearance of devices for packaging cosmetics.
Nevertheless, there exists a need to create novel optical effects so as to make such devices even more attractive to the consumer.
In addition, known methods do not give complete satisfaction since marking can be observed on the surface of certain articles due to the flow of the material during molding, and that detracts from the appearance thereof.